1. Industrial Useful Field
This invention relates to a twin clutch having two clutch discs with an intermediate plate held between a pressure plate and a flywheel.
2. Prior Art
FIG. 10 is a vertical sectional partial view showing a conventional twin clutch. This twin clutch is of a pull-type having such a structure as fitting a roll pin to an intermediate plate so that a disengaging allowance of the intermediate plate can be secured and the intermediate plate can follow up wear of facings of clutch disc. In this figure, 1 is a flywheel, 2 is a pressure plate, 3 and 4 are clutch discs, 5 is an intermediate plate, 10 is a clutch cover and 30 is a diaphragm spring. The clutch cover 10 is bolted rigidly to the flywheel 1 through a flywheel ring 11 to compose a flywheel assembly. The flywheel ring 11 consists of a disc-like annular body 11a and bosses 11b protruding in an axial direction at circumferential plural places of the body, and the bosses 11b are bolted to the flywheel 1. The intermediate plate 5 is connected through an elastic strap (not shown) to the flywheel ring 11 so that it can not rotate relatively to the flywheel ring 11 but can move in the axial direction relatively thereto. The pressure plate 2 is connected through an elastic strap (not shown) to the clutch cover 10 so that it can not rotate relatively to the clutch cover 10 but can move in the axial direction relatively thereto. Consequently, both the pressure plate 2 and the intermediate plate 5 are urged axially to the the clutch cover side by the elastic straps respectively. Bosses 13 protruding outwardly in radial directions are provided at plural places of an outer periphery of the intermediate plate 5, and roll pins 50 are fitted in and through the bosses 13 in the axial direction. The roll pin 50 can slide relatively to the boss 13, and a load (sliding load) necessary for its sliding is so preset as to be larger than an elastic force of the elastic strap which urges the intermediate plate 5, and smaller than a pressing force applied from the diaphragm spring 30 onto the pressure plate 2. The roll pin 50 is installed in such a way that, at time of clutch engagement, one-side end face 50a is made contact with the flywheel 1 and a clearance .delta. forming the engaging allowance of the intermediate plate 5 is secured between the other-side end face 50b and the body 11a. The engaging allowance means an axial moving distance required for the intermediate plate 5 in a clutch engaging state to become a clutch disengaged state wherein it does not contact with the clutch discs 3 and 4 on both sides thereof.
In a clutch disengaging operation of such a twin clutch, when an inner peripheral part of the diaphragm spring 30 moves backward in the axial direction (to the clutch cover 10 side), both the pressure plate 2 and the intermediate plate 5 are moved backward by means of the respective elastic forces of the elastic straps. Thereby, the the clutch disc 3 is first disengaged from the flywheel 1, and the intermediate plate 5 is then disengaged from the clutch disc 3. In this instance, the clutch disc 4 is still held between the pressure plate 2 and the intermediate plate 5. The intermediate plate 5 stops its motion when moving backward by a length corresponding to the distance .delta. because the end face 50b of the roll pin 50 comes in contact with the body 11a. And, only the pressure plate 2 moves from here on so that the clutch disc 4 is disengaged from the intermediate plate 5 and the pressure plate 2 is disengaged from the clutch disc 4. FIG. 11 shows relations of a releasing distance to moving distances of the pressure plate (PP) 2 and the intermediate plate (IMP) 5, at time of the disengaging operation of the clutch.
In a clutch engaging operation, when the inner peripheral part of the diaphragm spring 30 moves forward in the axial direction (to the flywheel 1 side), the pressure plate 2 is first moved together with the clutch disc 4 to the flywheel 1 side and the clutch disc 4 comes in touch with the intermediate plate 5 which has been in the stopped state caused by the end face 50b of the roll pin 50 contacting with the body 11a. Namely, the clutch disc 4 is first held between the pressure plate 2 and the intermediate plate 5, and the intermediate plate 5 is then moved together with the clutch disc 3 so that the clutch disc 3 comes in touch with the flywheel 1. That is, the clutch disc 3 is held between the intermediate plate 5 and the flywheel 1. In this way, the pressing force of the pressure plate 2 is transmitted to the both clutch discs 3 and 4 to cause the clutch to be engaged.
In the clutch engaged state, when the facings of the clutch discs 3 and 4 are worn out respectively, the boss 13 slides relatively to the roll pin 50 so that the intermediate plate 5 moves to the flywheel 1 side, and both the pressure plate 2 and the clutch disc 4 also move to the flywheel 1 side; because the end face 50a of the roll pin 50 contacts with the flywheel 1 and the sliding load of the roll pin 50 is so preset as to be smaller than the pressing force applied from the diaphragm spring 30 onto the pressure plate 2. Namely, both the pressure plate 2 and the intermediate plate 5 move to follow up the wear of facings of the clutch discs 3 and 4.